Touchscreen keyboard

ABSTRACT

Operating a touch-screen device includes displaying at least a portion of a keyboard on a touch-screen, detecting a touch on the touch-screen, and detecting movement of the touch on the touch-screen. Operating the touch-screen device also includes moving the displayed keyboard in response to the detected movement of the touch on the touch-screen, detecting a release of the touch from the touch-screen, and assigning a character according to a final location of the touch relative to a location of the displayed keyboard.

PRIORITY

This application is a continuation of and claims priority from U.S.patent application Ser. No. 14/324,282, filed Jul. 7, 2014, entitled“TOUCHSCREEN KEYBOARD”, which in turn claims priority from Great BritainPatent Application No. 1312184.3, filed Jul. 8, 2013, and all thebenefits accruing therefrom under 35 U.S.C. § 119, the entire contentsof all of the applications listed above being incorporated herein byreference.

BACKGROUND

The present disclosure relates generally to touch-screen technology and,more particularly, to a touch-screen device and method of operation.

In the mobile telephony world, touch sensitive devices enable softkeyboard usage, which keyboard is used for entering textual information,such as when a user is filling in a web form or sending a message. Softkeyboards refer to a software implementation of an otherwisehardware-based keyboard. Soft keyboards can be shown on demand and canbe adapted to different locales and participants' preferences. Inaddition, an on-screen keyboard helps to support hardware sizereduction.

Soft keyboards are designed to fit entirely into the screen real estate,and oftentimes a mobile telephone is used in portrait mode. In such acontext, where a small portion of the screen is reserved for thekeyboard area, a user may experience difficulties in accurately typing akey that is not readily seen, as the user's finger often occupies thespace of two or more keyboard letters. This can result in the userdepressing the wrong key.

SUMMARY

According to a first aspect of the present invention, there is provideda method of operating a touch-screen device. The method includesdisplaying at least a portion of a keyboard on a touch-screen of thetouch-screen device, detecting a touch on the touch-screen, anddetecting movement of the touch on the touch-screen. The method alsoincludes moving the displayed keyboard in response to the detectedmovement of the touch on the touch-screen, detecting a release of thetouch from the touch-screen, and assigning a character according to afinal location of the touch relative to a location of the displayedkeyboard.

According to a second aspect of the present invention, there is provideda touch-screen device. The touch-screen device includes a touch-screenand a processor connected to the touch-screen. The processor isconfigured to display at least a portion of a keyboard on thetouch-screen, detect a touch on the touch-screen, and detect movement ofthe touch on the touch-screen. The processor is also configured to movethe displayed keyboard in response to the detected movement of the touchon the touch-screen, detect a release of the touch from thetouch-screen, and assign a character according to a final location ofthe touch relative to a location of the displayed keyboard.

According to a third aspect of the present invention, there is provideda computer program product for operating a touch-screen device. Thecomputer program product includes a computer readable storage mediumhaving program instructions embodied therewith, the program instructionsreadable by a processing circuit to cause the processing circuit todisplay at least a portion of a keyboard on a touch-screen of thetouch-screen device, detect a touch on the touch-screen, and detectmovement of the touch on the touch-screen. The product further includesinstructions for moving the displayed keyboard in response to thedetected movement of the touch on the touch-screen, detecting a releaseof the touch from the touch-screen, and assigning a character accordingto a final location of the touch relative to a location of the displayedkeyboard.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the following drawings, in which:

FIGS. 1 to 4 are schematic diagrams of a touch-screen device; and

FIG. 5 is a flowchart of a method of operating a touch-screen device.

DETAILED DESCRIPTION

Embodiments of the present disclosure provide an improved on-screenkeyboard having relatively large keys and is straightforward to operate.The embodiments provide a means for helping users efficiently use softkeyboards and to minimize the number of incorrect inputs. The improvedtouch-screen device minimizes the number of input errors when touchingsoft keyboards for users whose fingers are too large for consistentlyaccurately selecting a key. Since a user's fingers cannot be madesmaller, the soft keyboard is enlarged thereby increasing the key sizeso that users can type without error.

Increasing the touch key size also implies increasing the size of thefull keyboard itself, such that the keyboard may no longer fit withinthe screen real estate, thereby resulting in out-of-screen keys notbeing directly accessible to the user. The embodiments described hereinprovide a keyboard that is ‘floatable’ within the screen bounds andmoves in such a way that as user's finger moves, the target key isdisplaced toward the moving finger. In other words, the user's fingerand keyboard move in opposite directions so that the finger and targetkey become closer.

According to some embodiments, a set of two events are used for thetarget key to be recognized, as compared to a fixed keyboard (which isentirely accessible), in that a single touch down event is sufficientfor a key to be selected. In the embodiments described herein, thetouch-screen device offers the user two capabilities: the capability tomake any key, including off screen keys, reachable by sliding thekeyboard in the opposite finger direction; and the capability to selectany available key, including accentuated popup characters. Both of thesecapabilities are handled using different touch events. The first eventis implemented by touch drag event recognition, and the second event isimplemented using touch up recognition. The touch down event is usedonly to initialize the starting point of the first drag vectordirection. In the case where the key is directly accessible to the user(no drag is involved) the user simply needs to act the same way as for anormal keyboard, the selected key being also recognized with the touchup event.

The touch-screen also offers the user the capability to adjust the fullkeyboard size by zooming the keyboard. This capability is handled usingthe recognition of a “pinch” gesture that consists in detecting twofinger gestures and calculating a zoom factor using the variation ofdistance between both the fingers on each drag event. Once the zoomfactor is obtained, the touch-screen device checks that the keyboardwidth is at least as large as the screen width and that the screenheight is at least as big as the keyboard height before zooming thekeyboard. This ensures that the keyboard remains usable.

When a user needs to select an accentuated character by using a popupsub keyboard containing all of the accentuated derivatives from theselected character, the touch-screen device can track the change ofposition of the user's finger on a key over time and deduce that whilethis position does not change and the touch up event does not occur, thetouch-screen device can popup an accentuated characters sub keyboard, ifavailable, for the considered key. This allows the user to accessaccented characters, for example, while still offering the functionalityof allowing a larger keyboard to be used.

In an embodiment, the step of moving the displayed keyboard in responseto the detected movement of the touch on the touch-screen includesmoving the displayed keyboard in the opposite direction to the detectedmovement of the touch on the touch-screen and moving the displayedkeyboard an equal distance to the detected movement of the touch on thetouch-screen. As the user touches the touch-screen device with hisfinger and starts to move his finger across the touch-screen (in anydirection), the keyboard displayed on the touch-screen starts to move inan equal and opposite manner to the movement of the user's finger. Thiseffectively scrolls the keyboard across the touch-screen, allowing theuser to access those keys of the keyboard that are not currentlydisplayed on the touch-screen. The use of an equal and opposite rate ofmovement gives the most user friendly and logical movement of thekeyboard in response to the user's moving touch and provides the userwith an intuitive interaction with the soft keyboard of thetouch-screen.

Turning now to FIG. 1, a touch-screen 10 is provided. The touch-screendevice 10, here a mobile phone, has a touch-screen 12 occupying the vastmajority of the front of the touch-screen device 10. The user interactswith the touch-screen device 10 primarily by touching the touch-screen12 with his finger or with a suitable stylus, depending upon the type oftouch-screen 12 being used in the touch-screen device 10. Thetouch-screen device 10 is controlled by an internal processor, under theoperation of a suitable computer program, which is connected to thetouch-screen 12 and receives the user's inputs on the touch-screen 12and controls the output on the touch-screen 12 accordingly. The usercontrols the touch-screen device 10 by interacting with the touch-screen12.

The touch-screen device 10 is controlled by the processor to display asoft keyboard 14 on the touch-screen 12. The keyboard 14 is “soft” inthe sense that it is not a hardware keyboard such as used with aconventional desktop PC but is a software implementation of thekeyboard. Only a portion of the keyboard 14 is currently visible on thetouch-screen 12. This allows the individual keys 16 of the keyboard 14to be larger than would otherwise be the case if the entire keyboard 14was shown on the touch-screen 12. However, by enlarging the keys 16,certain keys 16 are not directly accessible to the user.

The soft keyboard 14 shown on the touch-screen 12 of the touch-screendevice 10 is a standard QWERTY keyboard that is very widely used in theWestern world. The vast majority of typewriters and computer keyboardsin the Western world use this layout of keys, which arranges the keysaccording to their frequency in the English language, mapping the commonkeys to the easiest position to find with the fingers of the user'shands. The common user will know that the layout of the keys of thekeyboard 14 imply that the remainder of the keys are (virtually) off thetouch-screen 12 to the right-hand side and cannot be directly accessed.

FIG. 2 illustrates how a user accesses a key that is not currentlyvisible on the touch-screen 12. In this example, the user wishes toaccess the key “P”, which is not part of the portion of the keyboard 14currently being displayed on the touch-screen 12. The letter “P” on astandard QWERTY keyboard is found on the top line of letters at thefurthest point to the right-hand side. It is not necessary that the userknow the exact location of the key in question, only that he be awarethat it is not currently visible. The user touches down on a firstletter (here the letter “Q”) and starts dragging his finger to theright.

When the user drags his finger towards the target letter, the keyboard14 is moved in the opposite direction to the movement of the finger,thereby showing parts of the keyboard 14 that were previously hidden. Inan embodiment, the movement of the keyboard 14 is equal and opposite tothe movement of the user's touch on the touch-screen 12. This provides asimple and intuitive movement of the keyboard 14, in response to thedetected movement of the user's touch on the touch-screen 12. The useris now able to reach those characters that were not previously directlyaccessible, as they were not part of the portion of the keyboard visiblefrom the starting position.

FIG. 3 shows the user continuing to drag his finger towards the targetletter “P”. The view shown in this Figure is an intermediate position,the letter “T” is currently highlighted, in order to show the currentkey 16 that the user is selecting. The keyboard 14 has moved to the leftin this Figure relative to the position of the keyboard 14 in FIGS. 1and 2. As the user continues to drag his touch to the right, then thekeyboard 14 will continue to move to the left in an equal and oppositemotion. The processor of the touch-screen device 10 controls thescrolling of the keyboard 14 in response to the detection of the user'smovement of his finger across the touch-screen 12.

Once the user has moved his finger across the touch-screen 12 to reachthe target letter, he can then release his finger in order to select thedesired character. FIG. 4 shows the user releasing his finger from thetarget letter “P”, which results in the processor of the touch-screendevice 10 assigning the character “P” according to the final location ofthe user's touch relative to the location of the displayed keyboard 14.As can be seen in this Figure, the letter “P” has now been displayed atthe text cursor and the user can continue selecting keys 16 of thekeyboard 14 to continue typing. If the user needs to select a key 16that is not currently visible, then as before, he can drag his finger onthe touch-screen 12 to cause the keyboard 14 to move in the oppositedirection to the drag movement.

FIG. 5 shows a flowchart summarizing the method of operating thetouch-screen device 10. The method includes, at block S5.1, displayingat least a portion of the keyboard 14 on the touch-screen 12. When theuser is operating the touch-screen device 10 in any mode that requires atext input, then the keyboard 14 is shown in a lower portion of thetouch-screen 12, as illustrated in FIG. 1. This portion of the keyboard14 that is shown is either a predefined start portion or is the lastdisplayed portion, from the user's last interaction with the keyboard14.

At block S5.2, a touch is detected on the touch-screen 12. This touchcould be with the user's finger or with a stylus; this is not materialto the operation of the method. At block S5.3, movement of the touch onthe touch-screen 12 is detected, which indicates that the user isperforming a dragging motion of his finger (or stylus). At block S5.4,the displayed keyboard 14 is moved in response to the detected movementof the touch on the touch-screen 12. As discussed above, in anembodiment, this movement is equal and opposite to the detected movementof the touch on the touch-screen 12.

At block S5.5, the release of the touch from the touch-screen 12 isdetected, and at block S5.6, a character is assigned according to thefinal location of the touch relative to the location of the displayedkeyboard 14. Once the processor of the touch-screen device 10 detectsthat the user's touch has been released, then a character is assigned tothe touch, according to the position of the last touch relative to thekeyboard's position as currently displayed on the touch-screen 12. Inthis way, an improved input method is delivered, which can userelatively larger keys on the keyboard and can still provide the userwith easy access to all of the keys of the keyboard.

The processor of the touch-screen device 10 may operate the followingpseudo-code in controlling the operation of the touch-screen 12:

1. layout the keyboard

2. adjust the keyboard size so that its height fits the screen heightand that the screen width is only a part of the keyboard width (amaximum of two vertically aligned keyboard corners must be visible atthe same time)

3. wait for an event (global event loop)

3.1. if a finger touch down appears

3.1.1. identify the letter under the finger (if any)

3.1.2. if the next event is a one finger drag event

3.1.2.1. calculate the finger position difference between this event andthe previous one: in other words, calculate the finger displacement

3.1.2.2. if the displacement is not zero

3.1.2.2.1. check whether any keyboard corner cannot move inside the viewas a result of this displacement and eventually modify the displacementvalues accordingly

3.1.2.2.2. move the keyboard in the opposite direction to the fingerusing the calculation result

3.1.2.2.3. identify the current overfly key

3.1.2.3. else if the finger is stationary for a sufficient amount oftime

3.1.2.3.1. process eventual accentuated character if available.

3.1.3. else if it is a one finger touch up event

3.1.3.1. identify the selected key and send it to the interestedcomponent

3.1.4. else return in the global event loop step

3.2. else if a screen orientation changes, return to the adjust toscreen step (step 2)

In this way, the touch-screen device 10 provides the improvedmethodology. Non-standard characters can be delivered by the process, asonce the user has scrolled the keyboard 14 to reach a desired key, if hemaintains his touch on the specific character for a short period oftime, a sub-keyboard is displayed by the touch-screen 12 and the usercan make a second touch on the sub-keyboard to indicate which characterhe wishes to select. All other normal functions on the keyboard 14 maywork as usual, such as backspace and return, and the user can accessthese functions by scrolling the keyboard with finger dragging to reachthese function keys in the same manner as described above.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present disclosure has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the disclosure in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure. Theembodiments were chosen and described in order to best explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various embodiments with various modifications as are suited to theparticular use contemplated.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), astatic random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The invention claimed is:
 1. A method for displaying a keyboard on atouch-screen device, the method comprising: displaying, by a processor,a first portion of the keyboard on a touch-screen of the touch-screendevice, the first portion of the keyboard containing a first corner ofthe keyboard and not containing a second corner of the keyboard opposingthe first corner, wherein the first corner and the second corner define,at least in part, an outer periphery of the keyboard; detecting, by theprocessor, a touch event on the touch-screen; detecting, by theprocessor, a drag operation on the touch-screen prior to detecting atouch-up event; determining, by the processor, a first touchdisplacement value associated with the drag operation; determining thatthe first touch displacement value is not sufficient to cause the secondcorner of the displayed keyboard to move into a viewing area of thetouch-screen; modifying the first touch displacement value to generate asecond touch displacement value associated with the detected movement ofthe touch, wherein the second touch displacement value is sufficient tocause the second corner to move within the viewing area, moving thedisplayed keyboard based at least in part on the second touchdisplacement value to cause a second portion of the keyboard to bedisplayed on the touch-screen, the second portion of the keyboardcontaining the second corner and not containing the first corner;detecting, by the processor, the touch-up event; determining, by theprocessor, a keyboard character associated with the touch-up event; anddisplaying, by the processor, the keyboard character on thetouch-screen.
 2. The method of claim 1, wherein scrolling the keyboardcomprises moving, by the processor, the keyboard on the touch-screen ina direction opposite to a direction of the drag operation.
 3. The methodof claim 1, wherein determining the first touch displacement valuecomprises calculating, by the processor, a distance between a startinglocation of the drag operation on the touch-screen and an endinglocation of the drag operation on the touch-screen, wherein the startinglocation of the drag operation corresponds to a location of the touchevent on the touch-screen.
 4. The method of claim 1, wherein thedisplayed first portion of the keyboard is a predefined portion or alast displayed portion corresponding to a last user interaction with thekeyboard.
 5. A touch-screen device, comprising: a touch-screen; a memorystoring computer-executable instructions; and a processorcommunicatively coupled to the touch-screen and the memory, wherein theprocessor is configured to access the memory and execute thecomputer-executable instructions to: display a first portion of akeyboard on a touch-screen of the touch-screen device, the first portionof the keyboard containing a first corner of the keyboard and notcontaining a second corner of the keyboard opposing the first corner,wherein the first corner and the second corner define, at least in part,an outer periphery of the keyboard detect a touch event on thetouch-screen; detect a drag operation on the touch-screen prior todetecting a touch-up event; determine a first touch displacement valueassociated with the drag operation; determine that the first touchdisplacement value is not sufficient to cause the second corner of thedisplayed keyboard to move into a viewing area of the touch-screen,modify the first touch displacement value to generate a second touchdisplacement value associated with the detected movement of the touch,wherein the second touch displacement value is sufficient to cause thesecond corner to move within the viewing area; move the displayedkeyboard based at least in part on the second touch displacement valueto cause a second portion of the keyboard to be displayed on thetouch-screen, the second of the keyboard containing the second cornerand not containing the first corner, detect the touch-up event;determine a keyboard character associated with the touch-up event; anddisplay the keyboard character on the touch-screen.
 6. The touch-screendevice of claim 5, wherein the processor is configured to scroll thekeyboard by executing the computer-executable instructions to move thekeyboard on the touch-screen in a direction opposite to a direction ofthe drag operation.
 7. The touch-screen device of claim 5, wherein theprocessor is configured to determine the first touch displacement valueby executing the computer-executable instructions to calculate adistance between a starting location of the drag operation on thetouch-screen and an ending location of the drag operation on thetouch-screen, wherein the starting location of the drag operationcorresponds to a location of the touch event on the touch-screen.
 8. Thetouch-screen device of claim 5, wherein the displayed first portion ofthe keyboard is a predefined portion or a last displayed portioncorresponding to a last user interaction with the keyboard.
 9. Acomputer program product for displaying a keyboard on a touch-screendevice, the computer program product comprising a computer readablestorage medium having program instructions embodied therewith, theprogram instructions readable by a processing circuit to cause theprocessing circuit to perform a method comprising: displaying a firstportion of the keyboard on a touch-screen of the touch-screen device thefirst portion of the keyboard containing a first corner of the keyboardand not containing a second corner of the keyboard opposing the firstcorner, wherein the first corner and the second corner define, at leastin part, an outer periphery of the keyboard; detecting touch event onthe touch-screen; detecting a drag operation on the touch-screen priorto detecting a touch-up event; determining a first touch displacementvalue associated with the drag operation; determining that the firsttouch displacement value is not sufficient to cause the second corner ofthe displayed keyboard to move into a viewing area of the touch-screen;modifying the first touch displacement value to generate a second touchdisplacement value associated with the detected movement of the touch,wherein the second touch displacement value is sufficient to cause thesecond corner to move within the viewing area, moving the displayedkeyboard based at least in part on the second touch displacement valueto cause a second portion of the keyboard to be displayed on thetouch-screen, the second portion of the keyboard containing the secondcorner and not containing the first corner; detecting the touch-upevent; determining a keyboard character associated with the touch-upevent; and displaying the keyboard character on the touch-screen. 10.The computer program product of claim 9, wherein scrolling the keyboardcomprises moving the keyboard on the touch-screen in a directionopposite to a direction of the drag operation.
 11. The computer programproduct of claim 9, wherein determining the first touch displacementvalue comprises calculating a distance between a starting location ofthe drag operation on the touch-screen and an ending location of thedrag operation on the touch-screen, wherein the starting location of thedrag operation corresponds to a location of the touch event on thetouch-screen.